The low level functions work similarly to Unity's built in Lerp and it is up to you to track and pass in elapsedTime and duration on every call. The functions take this form (or the logical equivalent for Bezier() and CatmullRom()).

transform.position = ease(start, distance, elapsedTime, duration);

For convenience in configuration you can use the Ease(EaseType) function to look up a concrete easing function: